In semiconductor manufacturing techniques, an inspection of a chip which is processed in a wafer state before dicing, has been performed.
To inspect each chip in a wafer state, electrical operations of each chip are examined by pressing an inspection probe on an electrode pad of each chip. At this time, a probe trace (needle trace) is formed on the electrode pad of the chip.
Patent document 1 discloses a technique to determine whether the examination is performed normally or not from a pattern of the needle trace image obtained by imaging the electrode pad.
To perform this type of examination accurately, it is necessary to accurately align the relative position of a wafer and a camera. For example, patent documents 2 to 5 disclose techniques to align a wafer position to a probe to inspect the wafer.
For example, the technique disclosed in the patent document 2, when performing probing, an image measuring camera images the trace that is placed by a probe on a substrate to be inspected, coordinates of the trace are measured by using the image taken. A position control unit compares specified coordinates and the coordinates of the trace measured by the image measuring camera to obtain a conversion equation [A] between a camera coordinate series and a probe coordinate series. Further, the image measuring camera measures a position of a mark for position correction placed on a known position on the substrate to be inspected. The position control unit compares the known coordinates of the position correction mark and the coordinates of the position correction mark measured with the image measuring camera to obtain a conversion equation [B] between the camera coordinate series and the substrate coordinate series. The position control unit combines the conversion equations [A] and [B] to obtain a coordinate conversion equation [C] between the substrate coordinate series and the probe coordinate series. The position control unit obtains a position of the probe in the substrate coordinate series using the conversion equation [C], and corrects the position of the probe against the substrate to be inspected.
Patent document 1: Japanese unexamined patent application publication No. 2005-045194.
Patent document 2: Japanese unexamined patent application publication No. H06-258394
Patent Document 3: Japanese unexamined patent application publication No. H9-199553.
Patent Document 4: Japanese unexamined patent application publication No. H11-31228.
Patent Document 5: Japanese unexamined patent application publication No. 2000-329521.